A bright organic NIR-II nanofluorophore for three-dimensional imaging into biological tissues

TLDR

Fluorescence imaging in the NIR‑II window (1000–1700 nm) offers high spatial resolution, low background, and deep tissue penetration due to reduced autofluorescence and scattering. The authors aim to develop a bright organic nanofluorophore, p‑FE, for high‑performance NIR‑II biological imaging. p‑FE was synthesized as a bright emitter (>1100 nm) suitable for one‑photon imaging in the NIR‑II range. Its bright NIR‑II emission enables non‑invasive in vivo tracking of mouse brain blood flow, one‑photon 3D confocal imaging of fixed brain vasculature to ~1.3 mm depth with sub‑10 µm resolution, and two‑color in vivo imaging with CNTs to highlight tumors.

Abstract

Abstract Fluorescence imaging of biological systems in the second near-infrared (NIR-II, 1000–1700 nm) window has shown promise of high spatial resolution, low background, and deep tissue penetration owing to low autofluorescence and suppressed scattering of long wavelength photons. Here we develop a bright organic nanofluorophore (named p-FE) for high-performance biological imaging in the NIR-II window. The bright NIR-II >1100 nm fluorescence emission from p-FE affords non-invasive in vivo tracking of blood flow in mouse brain vessels. Excitingly, p-FE enables one-photon based, three-dimensional (3D) confocal imaging of vasculatures in fixed mouse brain tissue with a layer-by-layer imaging depth up to ~1.3 mm and sub-10 µm high spatial resolution. We also perform in vivo two-color fluorescence imaging in the NIR-II window by utilizing p-FE as a vasculature imaging agent emitting between 1100 and 1300 nm and single-walled carbon nanotubes (CNTs) emitting above 1500 nm to highlight tumors in mice.